[leapingdog]

Change at tier one telecoms providers tends to be glacial. It follows hardware upgrade cycles that take ages to plan and implement.

I spent a decade writing element management systems. An element is a network device - switch, router, ROADM, etc. Often you give the customer kit & software and they spend a couple of years assessing it. This software would be installed on secure out of band networks with no route to the internet. 10/8 would have been adequate for the lifetime of the hardware currently in service - 200G stuff. However, that's not how things played out.

When I started working on EMS software IPv6 support was a requirement but it was just a box ticking exercise. No one was actually going to use it. A decade later IPv6 HAD to work for northbound and southbound traffic, on an internal network. Otherwise, no sale. IPv6 is being used in anger in telecoms. I have no idea how long that will take to filter to in band networks.